Use Stainless Steel Shells to Protect Connectors in Harsh Environments

Industrial and maritime environments are two of the most challenging for designers of electronic systems. Industrial and factory automation brings exposure to heat, moisture, dust, shock and vibration, water jets, and sanitizing chemicals. Maritime environments share many of the same issues, with the added twists of salt spray and bright sunlight. Regardless of the environment, electronics connectors must be well-protected to operate reliably and safely.

A connector’s housing is the key and first line of defense, enabling sealing and locking. Housings protect the connection from external effects such as humidity, water, dust, mechanical shocks, foreign bodies, cooling agents, sanitizing chemicals, and oil. They also shield against electromagnetic interference (EMI).

Let’s review the structure of connector shells and how they protect the vulnerable interior of a connector. We’ll then look at shell examples from Harting’s Han-INOX family of stainless steel hoods and housings.

The anatomy of a connector

A rugged connector set joins signals, power, or both (Figure 1). Inside the connector, the male and female inserts hold contacts that mate with the corresponding circuits. Water and other conducting liquids, and even high humidity with airborne particulates, can bridge the insulating layer and cause damage. This is where the connector shell comes into play.

Figure 1 : Shown are the elements of a typical multi-conductor connector. (Image source: Harting)

A connector shell typically has a hood for the mobile part of the wire connection and a cable clamp to hold the wire and provide strain relief. The cable clamp features a gland with either a single or multiple seals to protect the cable entry against dust and liquids. The housing is the fixed part, which is usually hard-mounted to a bulkhead or panel. In the case of cable-to-cable connections, the shell may consist of top and bottom hoods. Connector hoods and housings designed for harsh environmental exposure are made of stainless steel, as it is a mechanically robust material resistant to chemicals, salt water, and corrosion, providing a long lifespan in hostile environments.

The male and female inserts, with the associated contacts, fit into the hood and housing. The shell features a locking mechanism designed to secure the two elements together, even in the presence of shock and vibration. Fluoro-rubber seals join the hood to the housing and the housing to the mounting surface. These all-weather seals have outstanding properties, including high resistance to heat, ozone, and many chemicals.

Rating the quality of a seal

The quality of the seal in a connector is determined by its ingress protection (IP) rating. The IP rating is a two-digit number. The first number represents protection against solid particulate matter, such as dust and sand, and can range from 0 to 6, with 0 indicating no protection and 6 representing total protection. The second number is the degree of protection from water. This scale ranges from 0 to 9, with 0 indicating no protection and 9 indicating protection from water delivered from a high-pressure steam jet cleaner. A rating of IP65 represents a water-resistant connector able to withstand water from a hose applied in any direction. A rating of IP67 represents a waterproof connector that can withstand temporary immersion.

Examples of stainless steel connector shells

Connector shells are designed to fit the contact inserts. For example, the Harting 19440031750 (Figure 2) is a cable-to-cable stainless steel coupling hood.

Figure 2: The 19440031750 stainless steel coupling hood is intended for cable-to-cable applications. (Image source: Harting)

This hood is sized to match the Harting 3A contact inserts, comes with a matte finished surface, and includes a single-lever central position locking clip. When outfitted with inserts and seals, and then mated, it has an ingress protection rating of IP67.

The mating 19440031440 hood (Figure 3) features locking studs that engage the locking clip on the coupling.

Figure 3: The 19440031440 hood locks with a compatible single lever coupling hood. (Image source: Harting)

Both shells have threaded openings, in this case at the top, to accept a cable clamp and cable gland. The locking stud shell is also available with an alternative side-entry cable port.

To accommodate larger B24 series contact inserts, designers can opt for the 19440240427 (Figure 4). This hood also features a top-entry cable port and dual locking studs.

Figure 4: The 19440240427 hood accepts B24 contact inserts and is dust-tight and water-resistant. (Image source: Harting)

The 19440240427 connector hood is available in a version with a side-entry port and is IP65 rated.

The compatible B24 box or bulkhead mounting base for the 19440240427 is the 19440240301 (Figure 5).

Figure 5: The B24-compatible 19440240301 base features a dual locking configuration and is rated IP65. (Image source: Harting)

It shares the IP65 rating and features a dual locking lever configuration to hold the mated hood. Like the body of the base, the locking levers are made of stainless steel.

The 19440160527 (Figure 6) is an example of a side-entry hood that houses a B16 contact insert. It has an IP rating of IP65 and also features a dual locking configuration.

Figure 6: The B16-compatible 19440160527 hood features a side-entry port and uses a dual locking configuration. (Image source: Harting)

The compatible B16 base for the 19440160527 is the 19440160301 (Figure 7) panel or bulkhead-mounted base. This base features a bottom insert entry opening and is IP65 rated.

Figure 7: The 19440160301 B16 base also uses dual locking levers. (Image source: Harting)

Conclusion

From industrial to marine applications, designers need to be assured that their electrical connections are safe and reliable. Harting Han-INOX stainless steel connector shells protect connectors against mechanical shock, dust, water, or corrosive chemicals in the harshest operating environments.